diff --git a/source/blender/editors/object/object_shapekey.cc b/source/blender/editors/object/object_shapekey.cc
index 32b2f380f89..f43d91b927a 100644
--- a/source/blender/editors/object/object_shapekey.cc
+++ b/source/blender/editors/object/object_shapekey.cc
@@ -867,6 +867,8 @@ static bool shape_key_make_basis_poll(bContext *C)
 static wmOperatorStatus shape_key_make_basis_exec(bContext *C, wmOperator * /*op*/)
 {
   Object *ob = CTX_data_active_object(C);
+  Key *key = BKE_key_from_object(ob);
+  KeyBlock *old_basis_key = static_cast<KeyBlock *>(key->block.first);
 
   /* Make the new basis by moving the active key to index 0. */
   const int from_index = -1; /* Interpreted as "the active key". */
@@ -880,6 +882,14 @@ static wmOperatorStatus shape_key_make_basis_exec(bContext *C, wmOperator * /*op
     return OPERATOR_CANCELLED;
   }
 
+  /* Make the old & new basis keys "Relative to" the new basis key. For the new key it doesn't
+   * matter much, as it's treated as special anyway, but keeping it relative to another key makes
+   * no sense. For the old basis key (which just became a normal key), it would otherwise still be
+   * relative to itself, effectively disabling it. */
+  KeyBlock *new_basis_key = static_cast<KeyBlock *>(key->block.first);
+  new_basis_key->relative = 0;
+  old_basis_key->relative = 0;
+
   DEG_id_tag_update(&ob->id, ID_RECALC_GEOMETRY);
   WM_event_add_notifier(C, NC_OBJECT | ND_DRAW, ob);